Sarai Sierra, who is 33, arrived in Istanbul on Jan. 7. She was supposed to return to New York on Jan. 21 but was not on her flight home. (PHOTO: ABC News)

Sarai Sierra, who is 33, arrived in Istanbul on Jan. 7. She was supposed to return to New York on Jan. 21 but was not on her flight home and has not been heard from since.

A police official said Monday authorities are reviewing security camera footage from around her hostel's neighborhood. The official said no trace of her has been detected yet. He spoke on condition of anonymity in line with government rules.

Sierra's husband and brother are traveling to Istanbul to help the search.

Before she went missing, Sierra told relatives she planned to take photographs at a tourist destination.